Improvement in stove-pipe thimbles



M. N. COBB.

STOVE-PIPE THIMBLE.

No.178,510, .Patented JunelS, 1876.

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` TENT Crrrc MEBRITT N. COBB, STONEHAM, MASSACHUSETTS.

IMPROVEMENT IN STOVE-PIPE THIMBLES.

Specification forming part of Letters Patent No. 178,510, dated June 13, 1876; application led December 16, 1875.

. To all whom t may concern specification My invention relates to means of improving defective drafts in chimneys ofbuildings; and consists, rst, in an open thimble having a projecting under side; and, second, in a thim` ,ble having a projecting underside, and provided with holes in said under side, as hereinafter described.

The accompanying drawings represent my invention, Figure 1 being a plan view of the same; and Fig. 2 representing a chimney, with a portion brokenout to show the position 0f the thimble vin the chimney.

A represents the walls of a chimney; B and C, the inner space of the chimney above and below the bottom of the thimble D, respectively. The thimblc D is a hollow cylinder, of cast or sheet metal, extending from the outer surface of the chimney into the chimney, and about two-thirds of the way across the interior of the same; only the lower part of the thimble, however, extends thus far, the upper port-ion of the thimblebeing cut away from the inner surface of the chimney to the free end of said thimble,' as shown in the drawings. Both ends of said thimble are entirely open. Three circular holes are made in the bottom of the thimble, each hole being about three-eighths of an inch in diameter. The projecting'under'portion of the thimble conducts the heated current of air from the re into the middle of the chimney, where there is less friction than at the sides, and divides the heated air from the cold air below, and by this means creates a strong draft. The holes E E allow sufficient air from below to rise through the lower side of the thimble, and prevent the deposition of ashes in the thimble. The number of holes depends upon the amount of space in the chimney below the thimble. No exact rule for the number of holes can be given. I use at least three holes; lout if the depth of the chimney below the thimble is greater than four feet, I use four holes, and `an additional hole for every three feet, or thereabout, of increased depth.

The thimble herein described may be set permanently, or may be put into the thimble usually found in chimneys; or the same result may be accomplished by cutting the end of the stove-pipe into the shape of the thimble, and projecting the end into the chimney.

I claim as my inventionl. The thimble D, having its under side extended parallel to the axis of the thimble, as and for the purpose described.

2. The thimble D, having the projecting under side andthe holes E E, as and for the purpose described.

MERRITT N. COBB. Witnesses:

ALBERT M. MOORE, HABLAN P. YOUNG. 

